Step 9: Assemble and create the transmitter - 3 Now we will build the voltage divider. Take the two 10K resistors and connect them as shown. One goes from AD0 and one from AD4 . Both then connect to ground. Conveniently, the chip we are not using had grounded pins so we can 'reuse' those pins. Now comes the tricky part. We want to connect the other end of the 4.7K resistor to the AD0 pin but the 10K resistor is already there. Use your soldering iron to melt a blob of solder onto the top of the 10K resistor and then piggyback the 4.7K resistor by soldering to the top of the 10K resistor. Solder the orange wire to the AD0 pin, the yellow to the AD4 The other two wires are for carrying power. The red wire should be soldered to the +5V pin on the bottom of the adapter PCB. The brown wire to the GND pin. We're nearly done with the adapter soldering. Lastly is the 220uF reset capacitor. We'll connect this to the RST pin, 5th from the top on the left. Make sure the long lead is connected to the RST pin and the shorter lead goes to the 4th pin of where the chip would go. Check the photo on the left to make sure you've got it in right. The capacitor wont fit underneath the XBee module so give it some lead length so that the cylindrical bulk is next to the 3.3V regulator. For reference, the images below show what the back should look like. ... and what it should look like with the XBee modem installed. Make sure the pins on the XBee line up with the header.
http://www.instructables.com/id/20-Unbelievable-Arduino-Projects/